The manufacture of microchips and some other industrial products has created a necessity for an extreme degree of cleanliness in manufacturing facilities, commonly called clean rooms. As a result of these cleanliness requirements, Federal standards have been promulgated and must be strictly complied with by the industries involved. Current Federal Standard No. 209B pertaining to classes of room cleanliness establishes three classes of clean rooms, Class 100 being the strictest of these classes. Class 100 specifies that only 100 particles of 0.5 micron size or larger are allowed per cubic foot of air in the clean room. The standard does not pertain to merely an average foot of air but to any cubic foot, at any time. Suggested air velocities are also listed for each class under Federal Standard No. 209B.
A main object of the present invention is to fully comply with and substantially exceed the requirements of Class 100 under Federal Standard No. 209B, in connection with upholstered furniture for clean room use, such as chairs, stools and other seat structures.
Presently, no conventional upholstered furniture or wooden furniture can be tolerated in clean rooms because of the micro particles expelled by them into the environment during normal usage. Such furniture falls far short of even the most liberal class under Federal Standard No. 209B, namely Class 100,000. Metal furniture, such as furniture made entirely of stainless steel, can meet the Federal standards but such furniture becomes so uncomfortable during long usage as to be intolerable, and does not represent a complete solution to the problem.
A further object of the present invention is to provide comfortable upholstered furniture, including various types of seats for clean room usage which fully comply with and exceed the cleanliness requirements under Federal standards or self-imposed industrial standards.
Another object of the invention is to provide seat cushions or seat backs in upholstered forms which include sealed air-impermeable coverings for the yielding cushions and hard base members thereof, in conjunction with a highly efficient filter element through which all air must flow when leaving or entering the upholstered furniture structure.
The filter element embodied in the invention is either a hydrophilic or hydrophobic sheet element possessing the ability to exclude particles as small as 0.2 microns from passing through the filter elements, thus exceeding substantially the requirements of Class 100 under Federal Standard No. 209B.
The sheet filter element is interposed between the hard panel member of the seat or other body support component of upholstered furniture and the exterior air-impermeable cover. Breathing apertures are provided in the hard panel member and cover which may be in registering or non-registering staggered relationship. In either case, air leaving or entering the structure through the breathing openings must also traverse the filter element, thus preventing particle contamination of the surrounding environment.
Other features and advantages of the invention will become apparent to those skilled in the art during the course of the following detailed description.